A CRT Driver Board Kit?

At Maker Faire, a lot of people asked me if I had a kit available for any of my CRT clocks. Based on the amount of interest, I’ve decided to put together a kit that will make it easy for people to drive cathode ray tubes using simple digital or low voltage analog control signals. The kit will include a PC board and all the components as well as detailed assembly instructions. For people that opt to use the digital interface, the kit will also include source code libraries making it easy to generate simple vector graphics.

The kit will use surface mount components, but none smaller than 0805. The ICs will be SOIC or SOTs, with the exception of the DAC, which is TSSOP.

Because this would be the very first surface mount kit many people attempt, I’m trying to figure out an approach for the assembly instructions that will make it easy to succeed. Some ideas I’ve had so far are:

Solder the DAC first since it has a fairly fine pitch package (TSSOP). The kit might include a second DAC as a spare. By soldering it first, it’s easier to check for short circuits and open circuits. Another approach is to make a “spare parts kit” available that has some of the commonly “blown” parts.

Assemble the kit in sections, testing the circuit a piece at a time. For example, after assembling the DAC, you would assemble the filament power supply and then test it to make sure it works and outputs the proper output voltage. This makes it easy to correct any mistakes as they occur. I don’t want people to assemble the whole board, throw the switch, and not have a working kit–or worse yet, have the kit go up in smoke.

It makes sense to release the assembly instructions on a site like Instructables, where it’s easy to include detailed macro photos of critical assembly details (like diode orientation). It also makes it easier to correct the instructions for mistakes, and it avoids the environmental impact of including printed instructions with the physical kit.

Hobbyists seem to have an aversion for surface mount components. With a little practice, I’ve found that it’s faster and easier to use surface mount components. Think about all the time you could save by not having to bend and clip resistor leads. You can solder most of the components without having to flip the board over.

If you have any ideas, please feel free to comment. This is all still in the early stages so there is plenty of room to change things and try new approaches.

Do it! There are way too few surface mount kits out there, other than just blank PCBs you have to source all the parts for individually.

As far as the spare IC thing, as long as they are reasonably priced in single quantities on Digikey, I might just say if you hose it, reorder there. Maybe just have some spares of the passives in case you lose a few resistors? At 0.2 cents, spares of those probably won’t move the kit price much…

eric :

Only issue with Digikey is the minimum order. For passives (and the real tiny components) I’ll include a few extras just in case. The real issue seems to be bagging and tagging each distinct part number. I’ll have to order reels of parts to keep the costs down, but the kit will need individual bags for components to make things easy to assemble. It would not be fun to have to read all the tiny numbers on surface mount resistors, and surface mount capacitors aren’t even marked at all.

klif :

I like to buy the kit for the CRT DRIVER BOARD as i collect CRT’s and i like to build this circuit,i have build some and worked fine but i will build also the one you will have for sale,so when it is ready just send me an email please…
If you like to see my collection just go to http://www.qrz.com and put 9H1GT…

Many thanks
regards
Joe

Klaus :

Very cool! Hope this comes together. When I’ve ordered samples from semiconductor manufacturers (or small quantities from Digikey/Allied/Mouser) I generally get cut tape from off the reel. Just snip the required amount, stick it in a snack-size ziplock, and pop a printed label on. You can always combine hard to mistake components in one bag, you know.

I just got some Schmartboards to make testing chips easier when I create a design. It looks better than most other solutions, but I haven’t had a chance to try them out yet. At any rate, they provide grooved boards to make soldering the ICs easier. Just a thought.

Thanks for the update. Any chance you could post a schematic, parts list, or PCB layout for comments and research? I’m building a pair of CRT driver boards of my own to get an old CK1414 “Symbolray” monoscope working again, and I’m looking for ideas to level shift the modulation/intensity grid signal, offset the heater appropriately, and come up with a regulated high voltage supply. I have ideas for all of these, but it looks like you’re farther along.

eric :

I’ll think about it, but I’d like to revisit the design at some point. The power supply is a bit complicated and I am thinking about replacing it with an Emco module to make the kit easier to build. The deflection plate drivers also involve a ~1000V level shifter with a lot of stacked transistors, and I think I can improve it.

The gun circuit uses the TV-style grounded grid with the cathode driven by a fast class A amplifier. The only issue there is that the circuit won’t work with CRTs that tie the cathode to one of the heater connections. I could solve that by moving to an isolated filament power supply circuit, but again, that’s just adding complexity.

Robert :

Very interesting thread! I have built one of Jon Stanley’s deflection amp/power supply designs and they work great but wanted to make a SMPS high voltage supply. Been experimenting on toroid transformer designs..That EMCO supply is nice but the price point is too high for me. CCFL’s have some promise but they are too weak since i want to drive the filament as well from the SMPS. I am using a LM2586s-12 as the driver…also trying combination of SG3524N with IRF740 or something similar…

Jason :

What John said! I’d love to see a schematic or some more details about this project. I don’t really have the skills to design a HV SMPS yet. Any chance Eric thst you could give a tip on the model CCFL transformer you chose for this project?